Better to Use Return Code or wc -l Output?


 
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# 1  
Old 04-23-2013
Better to Use Return Code or wc -l Output?

Hey All,

Quick question...

I'm writing a short script to check if a continuous port is running on a server.

I'm using "ps -ef | grep -v grep | grep processName" and I was wondering if it was better/more reliable to just check the
return code from the command or if its better to pipe to 'wc -l' and check if it is '1' or not?

I was just curious if one method was more reliable then the other?

The server is "AIX 6"...

Thanks in Advance,
Matt
# 2  
Old 04-23-2013
They both do the exact same thing, but the return code method is simpler and costs one less process. The simpler way tends to be the best.

However: You're putting yourself through a lot of needless pain here:

Code:
if pgrep processName >/dev/null
then
...
else
...
fi

You should find pgrep in most places.
This User Gave Thanks to Corona688 For This Post:
# 3  
Old 04-23-2013
Hey Corona, thanks for the reply!

Ok cool... I've never used "pgrep" before, thanks I'll give that a try.

Thanks Again,
Matt
# 4  
Old 04-23-2013
also, pgrep directly prints pid's, so if you need them as output it can be used unfiltered.
# 5  
Old 04-23-2013
Ugghhh, nevermind....

Looks like the UNIX server (which is probably older then myself, or pretty darn close) doesn't have the pgrep command.

It only has: grep, egrep, fgrep and zgrep...
Code:
ls -l /usr/bin | grep "grep"
-r-xr-xr-x    3 bin      bin           34052 Jan  7 2011  egrep
-r-xr-xr-x    3 bin      bin           34052 Jan  7 2011  fgrep
-r-xr-xr-x    3 bin      bin           34052 Jan  7 2011  grep
lrwxrwxrwx    1 root     system           27 May 12 2012  zgrep -> /usr/opt/freeware/bin/zgrep

Oh well, thanks anyways... I'll probably be able to get some use out of that on a slightly newer server. I guess I'll just go with the original idea.



Thanks Again,
Matt
# 6  
Old 04-23-2013
Quote:
Originally Posted by mrm5102
Ugghhh, nevermind....

Looks like the UNIX server (which is probably older then myself, or pretty darn close) doesn't have the pgrep command.
What is it? uname -a It'd be useful to know where pgrep is absent... I thought it was somewhat universal.
# 7  
Old 04-23-2013
Yea I thought the same thing...

It's a pretty ancient system that I "think" we plan on replacing soon... FINGERS CROSSED!
Running mostly dreaded UniData stuff.

Code:
#uname -a
AIX hostName 1 6 00C595524C00

No worries though I should be fine with the 'ps | grep' commands...


Thanks Again,
Matt
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